1. Field of the Invention
This invention relates generally to a counter of objects being transported by transport equipment, and more particularly to a counter of objects being transported in which the quantity of the objects being transported is counted by projecting a light beam onto the objects being transported, which are moving in a feathered state, that is, with the ends or corners thereof disposed continuously at certain intervals, and detecting the sharp changes in the level of the light reflecting point caused by the difference in the height of the objects being transported.
2. Description of the Prior Art
Counters of objects being transported, such as printed matter, which are moved by transport equipment, can be roughly divided into the contact type and the non-contact type which includes the proximity sensor type and the photosensor type.
Among them, the photosensor type, which is capable of counting objects without making contact therewith, is most commonly used.
The photosensor type counters include the light transmission type, the light reflecting type and other various variations, including apparatuses as disclosed in Japanese Patent Publication No. 770 of 1968 or Japanese Patent Publication No. 30334 of 1971.
The apparatus disclosed in Japanese Patent Publication No. 770 of 1968 counts the quantity of objects being transported by projecting a light beam onto the objects, amplifying the output obtained by detecting the reflected light beam within a predetermined range, and generating pulses in accordance with the number of the objects.
Since such counters, which generate pulses based on the detected intensity of the reflected light, require the surface condition, that is, color tone (lightness, saturation and hue) and roughness, of the objects being transported to be kept in a predetermined range, they lack in versatility and cannot ensure good counting performance, particularly in counting objects having different color tones.
The apparatus disclosed in Japanese Patent Publication No. 30334 of 1971 counts the quantity of objects being transported by intercepting a light path from a predetermined light source to a photoelectric transducer by the thickness of the objects.
In this type of apparatus, which intercepts the light path by the thickness of the objects, there is the need for controlling the travelling path of the objects so as to make sure that the objects intercept the fixed light path without fail. If objects being transported are made of a flexible material, controlling the travelling path may retard the flow of the objects, making counting impossible. Furthermore, relatively tight tolerances required for the thickness of the objects tend to limit the applicable types of objects being transported.